JP2014135878A - Controller of three-phase converter and electric power conversion system using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To converge a system to a target state in a short time.SOLUTION: The controller 100 of a three-phase converter that converts an AC voltage into a DC voltage. The controller 100 is configured to switch between closed loop control 62 that adjusts a voltage command value of each of U-phase, V-phase, and W-phase so that a detection value Va of a DC voltage approaches a predetermined target value and open loop control (64) that determines a voltage command value of each of U-phase, V-phase, and W-phase regardless of the detection value Va of the DC voltage. The controller 100 operates on open loop control when the detection value Va of the DC voltage is lower than the target value and subsequently operates on closed loop control.

Description

  The present invention relates to a controller for a converter that performs DC / AC conversion or AC / DC conversion.

  In the field of power electronics, power converters (converters) are widely used. Examples of the converter include an inverter that converts a DC voltage into a three-phase AC voltage and drives a three-phase load (for example, an electric motor), and a converter (rectifier) that converts a commercial AC voltage into a DC voltage and supplies the DC voltage to the load. .

JP-A-8-289599 Japanese Patent Laid-Open No. 11-146652

  When the converter receives a three-phase AC voltage and rectifies and smoothes it to convert it to a DC voltage, the DC voltage is generated by diode rectification and lower than its target value when the switching transistor of the converter is stopped It is in a state.

From this state, when the closed loop control is started so that the DC voltage approaches the target value, the deviation between the DC voltage and the target value becomes very large immediately after the start of the control. As a result, there is a problem that the control command value becomes large and overvoltage or overcurrent is likely to occur.
In a state where the deviation is large, the converter cannot output a sufficient voltage, and the control system may become unstable.
Further, in order to satisfy the control characteristics required in a state where the deviation is large, it is difficult to adjust the control gain (control parameter). Furthermore, the control gain determined so as to satisfy this requirement has a problem that the stability is emphasized and the responsiveness is deteriorated.

  The present invention has been made in view of such problems, and one of the exemplary purposes of an aspect thereof is to provide a controller for a converter that can converge the system to a target state in a short time.

  An embodiment of the present invention relates to a controller for a three-phase converter that converts an alternating voltage into a direct voltage. The controller controls the U-phase, V-phase, and W-phase voltage command values so that the detected DC voltage value approaches a predetermined target value, and the U-phase, Open-loop control that determines the voltage command value for each of V-phase and W-phase can be switched, and operates in open-loop control when the detected value of the DC voltage is lower than its target value, and then closed-loop control Works with.

  According to this aspect, immediately after the start of switching of the three-phase converter, in a state where the deviation between the detected value of the DC voltage and the target value is large, the three-phase converter is controlled by open-loop control, the DC voltage is increased, By switching to closed loop control after the deviation has decreased to some extent, overvoltage and overcurrent can be suppressed and the system can be stabilized in a short time.

  The controller may transition to closed loop control when the DC voltage reaches a threshold set near its target value.

  When the amplitude of the AC voltage is V and the frequency is ω, the voltage command values for the U-phase, V-phase, and W-phase in the closed-loop control are V · cos ωt, V · cos (ωt−2 / 3π), and V · cos, respectively. (Ωt−4 / 3π) may be set.

The controller converts the U-phase, V-phase, and W-phase current detection values Iu, Iv, and Iw from the uvw coordinate system to the dq coordinate system, and generates a d-axis current value Id and a q-axis current value Iq. Based on the coordinate converter, d-axis current value Id and q-axis current value Iq, d-axis current value Id target value Idr and q-axis current value Iq target value Iqr, d-axis voltage command value Vd and q-axis voltage command The target of the d-axis current value Id based on the first calculation unit that generates the value Vq, the feedforward unit that superimposes a predetermined number on the d-axis voltage command value Vd, the detected value Va of the DC voltage, and its target value Vr A second arithmetic unit that generates the value Idr, and the d-axis voltage command value Vd and the q-axis voltage command value Vq are converted from the dq coordinate system to the uvw coordinate system, and the U-phase, V-phase, and W-phase voltage command values Vu , Uvw / dq coordinate converter for generating Vv, Vw, Phase, V-phase, W voltage command value of phase Vu, Vv, and a pulse modulator for pulse-modulating the Vw, may comprise a. In the open loop control, the coefficient of the first calculation unit may be set to zero.
According to this configuration, open loop control can be realized by setting the coefficient of the first calculation unit to zero. Further, by optimizing the predetermined number E of feedforward, in open loop control, the voltage command values of the U phase, V phase, and W phase are changed to Ecosωt, Ecos (ωt−2 / 3π), Ecos (ωt−4 / 3π).

  The first computing unit generates a d-axis deviation that is the difference between the d-axis current value Id and the target value Idr, and the q-axis deviation that is the difference between the q-axis current value Iq and the target value Iqr. A second subtractor to be generated, a first proportional integration circuit that performs proportional / integral calculations on the d-axis deviation, a second proportional integration circuit that performs proportional / integral calculations on the q-axis deviation, and a q-axis current value Iq multiplied by ωL. A first multiplier, a first adder that generates a d-axis voltage command value Vd by adding the output of the first proportional integration circuit and the output of the first multiplier, and the d-axis current value Id is multiplied by -ωL. And a second adder that generates a q-axis voltage command value Vq by adding the output of the second proportional integration circuit and the output of the second multiplier. In the open loop control, the coefficient of the proportional term and the coefficient of the integral term of the first and second proportional integration circuits may be zero.

  Another aspect of this invention is related with a power converter device. The power converter includes a converter in which a three-phase AC terminal is connected to a three-phase AC power source and a smoothing capacitor is connected between the P-pole and N-pole power lines, and a U-phase, V-phase, and W-phase converter. A current detection unit that generates current detection values Iu, Iv, and Iw; a voltage detection unit that generates detection value Va of a DC voltage generated between the P-pole and N-pole power supply lines; and current detection values Iu, Iv, Iw, and A controller that generates U-phase, V-phase, and W-phase pulse-modulated control signals based on the detected value Va of the DC voltage; and a gate drive circuit that drives the converter based on the control signals from the controller. Also good.

  Note that any combination of the above-described constituent elements and the constituent elements and expressions of the present invention replaced with each other among methods, apparatuses, systems, and the like are also effective as an aspect of the present invention.

  According to the present invention, the system can be converged to the target state in a short time.

It is a block diagram which shows the structure of the power converter device containing a three-phase converter. It is a block diagram which shows the structure of a controller. It is a block diagram which shows the specific structural example of a controller. 4A is an operation waveform diagram of the controller of FIG. 2, and FIG. 4B is an operation waveform diagram of the conventional controller. It is a circuit diagram which shows the charging / discharging test | inspection system using a power converter device.

  The present invention will be described below based on preferred embodiments with reference to the drawings. The same or equivalent components, members, and processes shown in the drawings are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate. The embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

In this specification, “the state in which the member A is connected to the member B” means that the member A and the member B are electrically connected to each other in addition to the case where the member A and the member B are physically directly connected. It includes cases where the connection is indirectly made through other members that do not substantially affect the general connection state, or that do not impair the functions and effects achieved by their combination.
Similarly, “the state in which the member C is provided between the member A and the member B” refers to the case where the member A and the member C or the member B and the member C are directly connected, as well as their electric It includes cases where the connection is indirectly made through other members that do not substantially affect the general connection state, or that do not impair the functions and effects achieved by their combination.

  FIG. 1 is a block diagram showing a configuration of a power conversion device 2 including a three-phase converter. The power conversion device 2 includes a three-phase converter 10, a current detection circuit 20, an A / D converter 22, a gate drive circuit 24, a smoothing capacitor 26, a voltage detection circuit 28, an A / D converter 30, and a controller 100.

  The power converter 2 is used as a smoothing rectifier circuit that converts a three-phase AC voltage into a DC voltage and / or as an inverter that converts a DC voltage into a three-phase AC voltage.

  Three-phase converter 10 has a pair of upper arm switch 16 and lower arm switch 18 provided for each of power supply lines 12p, 12n, AC terminals 14u, 14v, 14w, U phase, V phase, and W phase.

  A three-phase power source or an input reactor (three-phase transformer) is connected to the AC terminals 14u, 14v, and 14w, and a three-phase AC voltage is input. Focusing on the U phase, an upper arm switch 16u is provided between the P-pole power supply line 12p and the AC terminal 14u, and a lower arm switch 18u is provided between the AC terminal 14u and the N-pole power supply line 12n. The same applies to the V phase and the W phase. The smoothing capacitor 26 is provided between the P-pole power supply line 12p and the N-pole power supply line 12n.

  The current detection circuit 20 detects currents flowing through the U-phase, V-phase, and W-phase AC terminals 14u, 14v, and 14w, respectively. As the current detection circuit 20, a current detection transformer (current transformer CT) is used. Alternatively, an impedance element (for example, a resistor) may be disposed in a current path that is symmetrical to the detection, and the current may be detected based on a voltage drop of the impedance element, and the method of detecting the current is not particularly limited.

  The A / D converter 22 receives analog voltages indicating the current detection values Iu, Iv, and Iw from the current detection circuit 20, converts them into digital values, and outputs them to the controller 100.

  The voltage detection circuit 28 detects the DC voltage Va between the P-pole power supply line 12p and the N-pole power supply line 12n. The A / D converter 30 receives the detection value Va corresponding to the DC voltage, converts it into a digital value, and outputs it to the controller 100.

  The controller 100 generates U-phase, V-phase, and W-phase pulse-modulated control signals Su, Sv, Sw based on the current detection values Iu, Iv, Iw and the voltage detection value Va. Gate driving circuit 24 drives upper arm switch 16 and lower arm switch 18 of converter 10 based on control signals Su, Sv, Sw from controller 100.

  The above is the overall configuration of the power conversion device 2. Next, the configuration of the controller 100 will be described. FIG. 2 is a block diagram showing the configuration of the controller 100. The controller 100 is a digital processing circuit, and may be, for example, a DSP (Digital Signal Processor) designed for exclusive use, may be configured by a combination of a general-purpose CPU and a program, or an FPGA (Field Programmable Gate Array). You may comprise using etc.

  The controller 100 includes a voltage command value generation means 60 and a pulse width modulator 38. The voltage command value generation means 60 generates voltage command values Vu, Vv, and Vw that indicate target voltage levels of the U-phase, V-phase, and W-phase AC terminals 14u, 14v, and 14w.

  The pulse width modulator 38 performs pulse width modulation on the voltage command values Vu, Vv, and Vw, and converts them into control signals Su, Sv, and Sw.

  The voltage command value generation means 60 is a closed loop control that adjusts the voltage command values Vu, Vv, and Vw of the U phase, V phase, and W phase by feedback so that the detected value Va of the DC voltage approaches a predetermined target value; Regardless of the detection value Va of the DC voltage, open loop control for determining the voltage command values Vu, Vv, Vw for the U phase, V phase, and W phase can be switched.

  The voltage command value generation means 60 includes a closed loop control means 62, an open loop control means 64, and a switching means 66. Based on the current detection values Iu, Iv, Iw and the voltage detection value Va, the closed loop control means 62 determines the voltage command values for the U phase, the V phase, and the W phase so that the detection value Va of the DC voltage approaches a predetermined target value. Vu, Vv, and Vw are generated by feedback.

  The open loop control means 64 is configured to be able to switch between open loop control for determining the voltage command values Vu, Vv, and Vw for the U phase, V phase, and W phase regardless of the detection value Va of the DC voltage. The

  The closed loop control means 62 and the open loop control means 64 may be configured as separate circuit blocks as shown in FIG. 2, or the functions of the common circuit blocks may be switched.

The switching means 66 switches between closed loop control and open loop control. When the closed loop control unit 62 and the open loop control unit 64 are configured as separate circuit blocks, the switching unit 66 includes a set of voltage command values Vu to Vw generated by the closed loop control unit 62 and the open loop control unit 64. One of the generated set of voltage command values Vu to Vw is selected and output to the pulse width modulator 38.
When the closed loop control means 62 and the open loop control means 64 are constituted by a common circuit block, and the function can be switched, the switching means 66 switches the function of the common circuit block.

  Specifically, the switching means 66 activates the closed loop control means 62 during a period in which the DC voltage Va is lower than its target value, and more preferably, the DC voltage Va is a threshold value near the target value. When the value Vth is reached, the open loop control means 64 is enabled.

  The amplitude of the AC voltage supplied from the circuit connected to the AC terminal 14 is V, the frequency is f, and the voltage of the AC terminal 14 of each phase is V · cos ωt, V · cos (ωt−2 / 3π), It is assumed that it changes according to V · cos (ωt−4 / 3π). At this time, the open-loop control means 64 converts the U-phase, V-phase, and W-phase voltage command values Vu, Vv, and Vw into V · cos ωt, V · cos (ωt−2 / 3π), and V · cos (ωt−4). / 3π).

  FIG. 3 is a block diagram illustrating a specific configuration example of the controller 100. The controller 100 includes a dq / uvw coordinate converter 32, a first calculator 40, a uvw / dq coordinate converter 36, a pulse width modulator 38, a feedforward unit 70, a second calculator 80, and a coefficient controller 90.

  The dq / uvw coordinate converter 32, the first calculation unit 40, and the uvw / dq coordinate converter 36 correspond to the closed loop control unit 62 and the open loop control unit 64 of FIG. In the circuit of FIG. 3, the function of the common circuit block (32, 40, 36) can be switched.

  The dq / uvw coordinate converter 32 converts the current detection values Iu, Iv, and Iw from the uvw coordinate system to the dq coordinate system, and generates a d-axis current value Id and a q-axis current value Iq. The signal processing and configuration in the dq / uvw coordinate converter 32 are not particularly limited, and since a known technique may be used, description thereof is omitted here. For example, the dq / uvw coordinate converter 32 may convert the uvw coordinate system into an αβ coordinate system that is a fixed coordinate system, and convert the αβ coordinate system into a dq coordinate system that is a rotating coordinate system that rotates at an angular velocity ω. .

  A filter that filters the current detection values Iu, Iv, and Iw and removes noise components thereof may be inserted before the dq / uvw coordinate converter 32.

  The first computing unit 40 determines the d-axis voltage command value Vd and the q-axis based on the d-axis current value Id, the q-axis current value Iq, the target value Idr of the d-axis current value Id, and the target value Iqr of the q-axis current value Iq. A voltage command value Vq is generated.

  Specifically, the first calculation unit 40 includes a first subtractor 42, a second subtractor 44, a first proportional integration circuit 46, a second proportional integration circuit 48, a first multiplier 50, a first adder 52, A 2 multiplier 54 and a second adder 56 are provided.

  The first subtracter 42 generates a d-axis deviation δd that is a difference between the d-axis current value Id and the target value Idr. The second subtractor 44 generates a q-axis deviation δq that is a difference between the q-axis current value Iq and the target value Iqr. The target value Iqr of the q-axis current is typically zero, but may be intentionally given a non-zero value.

  The first proportional integration circuit 46 performs a proportional / integral calculation on the d-axis deviation δd. The second proportional integration circuit 48 performs a proportional / integral calculation on the q-axis deviation δq. The first multiplier 50 multiplies the q-axis current value Iq by ωL. ωL is an impedance connected to the AC terminal 14, ω is an angular velocity of the AC signal, and L is an inductance. The first adder 52 adds the output of the first proportional integration circuit 46 and the output of the first multiplier 50 to generate a d-axis voltage command value Vd. The second multiplier 54 multiplies the d-axis current value Id by −ωL. The second adder 56 adds the output of the second proportional integration circuit 48 and the output of the second multiplier 54 to generate a q-axis voltage command value Vq.

Assume that the impedance connected to the AC terminal 14 is represented by R + L. The following relational expression holds between the d-axis component Id and q-axis component Iq of the current flowing through the impedance and the d-axis component Vd and q-axis component Vq of the voltage at the AC terminal 14.
Vd = (R + L · d / dt) × Id−ωL × Iq
Vd = ωL × Id + (R + L · d / dt) × Iq
The first calculation unit 40 converts the current command value into a voltage command value based on this relational expression.

  The feedforward unit 70 superimposes a predetermined number E on the d-axis voltage command value Vd generated by the first calculation unit 40. The feedforward unit 70 includes a third adder 72 that adds a predetermined number E to the output of the first proportional integration circuit 46. A third adder 72 may be provided between the first adder 52 and the uvw / dq coordinate converter 36 to add a predetermined number E to the output of the first adder 52.

  The predetermined number E is set substantially equal to the amplitude V of the AC voltage applied to the AC terminal 14. Thus, the voltage command values Vu, Vv, and Vw in the open loop control can be changed according to V · cos ωt, V · cos (ωt−2 / 3π), and V · cos (ωt−4 / 3π).

  The second calculation unit 80 generates a target value Idr of the d-axis current value Id based on the detected value Va of the DC voltage and the target value Vr. The second calculation unit 80 includes a third subtracter 82 and a third proportional integration circuit 84. The third subtracter 82 generates a voltage deviation δV that is a difference between the detected value Va of the DC voltage and the target value Vr. The third proportional integration circuit 84 performs a proportional / integral calculation on the voltage deviation δV to generate a target value Idr of the d-axis current value Id.

  The uvw / dq coordinate converter 36 converts the d-axis voltage command value Vd and the q-axis voltage command value Vq from the dq coordinate system to the uvw coordinate system, and U-phase, V-phase, and W-phase voltage command values Vu, Vv. , Vw is generated. The pulse width modulator 38 performs pulse modulation on the voltage command values Vu, Vv, and Vw of the U phase, V phase, and W phase, more specifically, pulse width modulation, and generates control signals Su, Sv, and Sw.

The coefficient control unit 90 switches the proportional term coefficient K _P and the integral term coefficient K _I of each of the first proportional integration circuit 46 and the second proportional integration circuit 48. Specifically, in a period for performing a closed loop control gives the design values of non-zero coefficients K _P, the K _I, in the period in which open loop control, coefficients K _P, a K _I is zero. That is, the coefficient control unit 90 corresponds to the switching unit 66 in FIG.

  The above is the configuration of the controller 100. Next, the operation will be described.

  FIG. 4A is an operation waveform diagram of the controller 100 of FIG. 2, and FIG. 4B is an operation waveform diagram of the conventional controller. First, the operation of the conventional controller will be described with reference to FIG.

Prior to time t1, the switching operation of the converter 10 is stopped, and the switching transistors 16 and 18 are all turned off. Therefore, diode rectification is performed by a diode provided in parallel with each transistor, and a DC voltage detection value (hereinafter, also simply referred to as DC voltage) Va is a voltage level obtained by rectifying and smoothing a three-phase AC voltage using a diode bridge circuit. Stabilized to V _RECT .

  At time t1, the switching operation of the converter 10 starts. The conventional controller generates the voltage command values Vu, Vv, and Vw so that their deviations become zero so that the DC voltage Va matches the target value Vr.

Immediately after the start of the switching operation, since the deviation between the DC voltage Va and the target value Vr is very large, the DC voltage Va greatly exceeds the target value Vr (overshoot). After that, the direct current voltage Va does not immediately converge to the target value Vr, but gradually approaches the target value Vr.
As described above, overshoot or the like occurs in the conventional controller. In addition, if the system is designed to operate stably with a large deviation immediately after startup, the settling time until the system state is stabilized becomes longer.

  Next, the operation of the controller 100 in FIG. 2 will be described with reference to FIG. The time before time t1 is the same as that shown in FIG. The controller 100 starts a switching operation by open loop control at time t1. By the open loop control, the DC voltage Va increases toward the target value Vr at a high speed. When the DC voltage Va reaches the threshold value Vth at time t2, the open loop control is switched to the closed loop control. Since threshold value Vth is set in the vicinity of target value Vr, deviation δV becomes small at the start of closed-loop control. As a result, the DC voltage Va converges to the target value Vr without overshooting.

The above is the operation of the controller 100 according to the embodiment.
The controller 100 according to the embodiment can suppress overvoltage and overcurrent.

  Further, the controller 100 according to the embodiment does not perform the closed loop control in a state where the deviation is large, so that the control system can be prevented from becoming unstable. From another point of view, the controller 100 can design the control characteristics considering only the state where the deviation δV is relatively small. Therefore, in the past, the stability of the system was prioritized and the response was sacrificed. In the controller 100 according to the embodiment, the control characteristics can be designed with priority on responsiveness, so that the system can be converged to the target state in a short time.

  Finally, the use of the power conversion device 2 will be described.

FIG. 5 is a circuit diagram showing a charge / discharge inspection system 600 using the power conversion device 2. The charge / discharge inspection system 600 includes a commercial AC power source 601, a charge / discharge inspection device 602, and a secondary battery 604.
The charge / discharge inspection device 602 receives the three-phase AC voltage from the commercial AC power source 601 and charges the secondary battery 604 (charging operation). In addition, the charge / discharge inspection apparatus 602 discharges the secondary battery 604 and recovers energy to the commercial AC power source 601 (discharge operation).

  The charge / discharge inspection device 602 includes a power conversion device 2, an input reactor 610, an insulating transformer 612, a smoothing capacitor 614, and a step-up / down converter 616. The input reactor 610 may be provided on the secondary side of the insulating transformer 612.

  A three-phase AC terminal of the converter 10 of the power conversion device 2 is connected to a three-phase commercial AC power source 601 via an input reactor 610 and an insulating transformer 612. Power supply lines 12p and 12n of converter 10 are connected to smoothing capacitor 614. The primary side (P) of the buck-boost converter 616 is connected to the smoothing capacitor 614, and its secondary side (S) is connected to the secondary battery 604.

During the charging operation, the power conversion device 2 rectifies the three-phase AC voltage. The DC voltage _VDC smoothed by the smoothing capacitor 614 is input to the primary side (P) of the buck-boost converter 616. The step-up / down converter 616 operates as a step-down converter having the primary side as an input and the secondary side as an output, and steps down the DC voltage _VDC to charge the secondary battery 604.

During the discharging operation, the step-up / down converter 616 operates as a boost converter having the secondary side as an input and the primary side as an output. Specifically, the battery voltage V _BAT is boosted, and the smoothing capacitor 614 is charged with the DC voltage _VDC . Converter 10 operates as an inverter, converts DC voltage _VDC to AC voltage, and outputs the AC voltage to commercial AC power supply 601 via insulating transformer 612 and input reactor 610.

  Even in such an application, the converter 10 can be suitably controlled by the controller 100 according to the embodiment.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are within the scope of the present invention. is there. Hereinafter, such modifications will be described.

(Modification 1)
In the embodiment, the case where the first calculation unit 40 and the second calculation unit 80 perform PI (proportional integration) control has been described, but P (proportional) control and PID (proportional integration differentiation) control may be performed.

(Modification 2)
In the embodiment, the vector control controller has been described as one specific example of the controller 100. However, the present invention is not limited to this, and can be applied to other controls such as V / F control. A person skilled in the art can optimally design the first calculation unit 40, the feedforward unit 70, the second calculation unit 80, and the coefficient control unit 90 according to the control method.

(Modification 3)
In the embodiment, the charge / discharge inspection apparatus has been described as an application of the power conversion apparatus 2, but the application is not particularly limited. The DC voltage may be supplied to an arbitrary load. Examples of the load include an inverter that drives a motor.

  Although the present invention has been described using specific terms based on the embodiments, the embodiments only illustrate the principles and applications of the present invention, and the embodiments are defined in the claims. Many variations and modifications of the arrangement are permitted without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 2 ... Power converter device, 10 ... Converter, 12 ... Power supply line, 14 ... AC terminal, 16 ... Upper arm switch, 18 ... Lower arm switch, 20 ... Current detection circuit, 22 ... A / D converter, 24 ... Gate drive circuit , 26 ... smoothing capacitor, 28 ... voltage detection circuit, 30 ... A / D converter, 32 ... dq / uvw coordinate converter, 34 ... phase compensator, 36 ... uvw / dq coordinate converter, 38 ... pulse width modulator, DESCRIPTION OF SYMBOLS 40 ... 1st calculating part, 42 ... 1st subtractor, 44 ... 2nd subtractor, 46 ... 1st proportional integration circuit, 48 ... 2nd proportional integration circuit, 50 ... 1st multiplier, 52 ... 1st adder 54 ... second adder, 56 ... second adder, 60 ... voltage command value generating means, 62 ... closed loop control means, 64 ... open loop control means, 66 ... switching means, 70 ... feed forward section, 72 ... first 3 adders, 8 ... second arithmetic unit, 82 ... third subtractor, 84 ... third proportional integral circuit, 90 ... coefficient control unit, 100 ... controller.

Claims (6)

A controller for a three-phase converter that converts AC voltage into DC voltage,
Regardless of the detected value of the DC voltage, the closed-loop control that adjusts the voltage command values of the U phase, the V phase, and the W phase so that the detected value of the DC voltage approaches a predetermined target value. It is configured to be able to switch between open-loop control and V-phase and W-phase voltage command values,
The controller, which operates in the open loop control in a state where the detected value of the DC voltage is lower than the target value, and then operates in the closed loop control.   2. The controller according to claim 1, wherein when the DC voltage reaches a threshold value set in the vicinity of the target value, the controller shifts to the closed loop control.   When the amplitude of the AC voltage is V and the frequency is ω, the voltage command values of the U-phase, V-phase, and W-phase in the closed-loop control are V · cos ωt, V · cos (ωt−2 / 3π), The controller according to claim 1, wherein the controller is set to V · cos (ωt−4 / 3π). Uvw / dq coordinate conversion for converting the U-phase, V-phase, and W-phase current detection values Iu, Iv, and Iw from the uvw coordinate system to the dq coordinate system to generate the d-axis current value Id and the q-axis current value Iq. And
Based on the d-axis current value Id, the q-axis current value Iq, the target value Idr of the d-axis current value Id, and the target value Iqr of the q-axis current value Iq, the d-axis voltage command value Vd and the q-axis voltage command value A first calculation unit for generating Vq;
A feedforward unit that superimposes a predetermined number on the d-axis voltage command value Vd;
A second calculator that generates a target value Idr of the d-axis current value Id based on the detected value Va of the DC voltage and the target value Vr;
The d-axis voltage command value Vd and the q-axis voltage command value Vq are converted from the dq coordinate system to the uvw coordinate system to generate U-phase, V-phase, and W-phase voltage command values Vu, Vv, and Vw. a dq coordinate converter;
A pulse modulator for pulse modulating the U-phase, V-phase, and W-phase voltage command values Vu, Vv, and Vw;
With
4. The controller according to claim 1, wherein in the open loop control, a coefficient of the first calculation unit is set to zero. 5. The first calculation unit includes:
A first subtracter that generates a d-axis deviation that is a difference between the d-axis current value Id and the target value Idr;
A second subtracter for generating a q-axis deviation which is a difference between the q-axis current value Iq and the target value Iqr;
A first proportional integration circuit that performs a proportional / integral calculation on the d-axis deviation;
A second proportional integration circuit for performing proportional / integral calculations on the q-axis deviation;
A first multiplier for multiplying the q-axis current value Iq by ωL;
A first adder that generates the d-axis voltage command value Vd by adding the output of the first proportional integration circuit and the output of the first multiplier;
A second multiplier for multiplying the d-axis current value Id by -ωL;
A second adder that generates the q-axis voltage command value Vq by adding the output of the second proportional integration circuit and the output of the second multiplier;
Including
5. The controller according to claim 4, wherein, in the open loop control, the coefficient of the proportional term and the coefficient of the integral term of the first and second proportional integration circuits are set to zero. A converter in which the three-phase AC terminal is connected to a three-phase AC power supply, and a smoothing capacitor is connected between the P-pole and N-pole power supply lines;
A current detection unit for generating U-phase, V-phase, and W-phase current detection values Iu, Iv, and Iw of the converter;
A voltage detection unit that generates a detection value Va of a DC voltage generated between the P-pole and N-pole power supply lines;
Based on the current detection values Iu, Iv, Iw and the detection value Va of the DC voltage, voltage command values for the U phase, V phase, and W phase are generated, and the U phase, V phase, A controller according to any one of claims 1 to 5, which generates a W-phase pulse modulated control signal;
A gate driving circuit for driving the converter based on the control signal from the controller;
A power conversion device comprising:

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